Being interrupted for just three seconds can double the chances of making a
mistake – which could prove deadly in some professions, psychologists have
claimed.

According to new research reading a text message, hearing a phone ring, or saying hello to a colleague is enough to put someone off their stride while concentrating on an important task.

For many professions, from doctors to those working on aircraft engines, that error could turn out to be fatal.

It is another reason why mobiles, background televisions and other potential distractions should be turned off completely during the times of concentration, the researchers from Michigan State University say.

Even the shortest of interruptions had “a surprisingly large effect” on an individual's ability to complete a task, according to the study published in the Journal of Experimental Psychology

During the study 300 volunteers were given a succession of letter combinations to type on a computer keyboard in the right order.

Some were deliberately interrupted and asked to type two other letters into the sequence before going back to their original instructions, with each intervention lasting, on average, 2.8 seconds.

Those who suffered no interruptions at all were likely to make a couple of mistakes, but those who experienced the short intervention saw their error rate double in comparison.

In many cases there would be no consequences but there are jobs, include surgeons and aeroplane mechanics, which require immense concentration where a mistake could prove to be disastrous, the researchers said.

Psychology Professor Erik Altmann, who carried out the study funded by the US Navy Office of Naval Research, said: "Why did the error rate go up? The answer is that the participants had to shift their attention from one task to another.

"Even momentary interruptions can seem jarring when they occur during a process that takes considerable thought. So before you enter this critical phase – all cellphones off, at the very least,"

He added: "What this means is that our health and safety is, on some level, contingent on whether the people looking after it have been interrupted."